Ultra-Processed Food: Correlation Without Cause

Hortus DeliciarumAn “impassioned polemic” is headed our way from British media doctor Chris van Tulleken and it aims to have us excise ultra-processed from our dietary habits. No doubt about it, ultra-processed food wins the prize for today’s best food boogeyman, but how wise is this bit of food fear based on correlation without a cause. Van Tulleken doesn’t need a causal mechanism to be confident they’re giving us heart attacks, high blood pressure, and obesity. It’s an article of faith.

But nutrition scientists from Purdue say “not so fast.” With a new critical review published by Advances in Nutrition, they tell us this rush to judgment is “imprudent.”

Where’s the Causality?

Vinicius Valicente and colleagues offer quite a thorough review of the ways that nutrition researchers suppose these ultra-processed foods are doing us harm. Is it their composition that causes the harm? Or the effect they have on food choice? Maybe they influence digestive processes in some way that interferes with healthy physiology.

The array of possibilities are enough to make us dizzy.

Yet none of these mechanisms are adequate to explain how the correlation of ultra-processed food with health issues might be a cause and effect relationship. These explanations simply don’t hold up to scrutiny. Valicente et al review the evidence for 15 purported mechanisms and find it to be insufficient for all of them.

Messaging More Compelling Than Evidence

This critical analysis tells us that the NOVA system for classifying ultra-processed food offers a compelling message that lacks a strong scientific foundation:

“Policy makers must use the best quality scientific data to translate complex evidence into simple and clear messages. NOVA already has a message that is intuitive, but it appears clearer than the data that support it.”

Thus, Valicente et al come to a simple conclusion:

“Because avoidance of ultra-processed food holds potential adverse effects (e.g., reduced diet quality, increased risk of food poisoning, food wastage), it is imprudent to make recommendations about their role in diets before causality and plausible mechanisms have been verified.”

Click here for the Valicente review, here and here for further perspective. For an engaging interview with Chris van Tulleken on his reservations about ultra-processed food, click here.

Hortus Deliciarum, illustration by Herrad of Landsberg / WikiArt

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April 22, 2023